1bi0
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(New page: 200px<br /><applet load="1bi0" size="450" color="white" frame="true" align="right" spinBox="true" caption="1bi0, resolution 2.3Å" /> '''STRUCTURE OF APO-AND ...)
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Revision as of 09:32, 20 November 2007
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STRUCTURE OF APO-AND HOLO-DIPHTHERIA TOXIN REPRESSOR
Overview
The diphtheria toxin repressor (DtxR) from Corynebacterium diphtheriae is, a divalent metal-activated repressor of chromosomal genes that encode, proteins responsible for siderophore-mediated iron uptake and also of the, gene of certain corynebacteriophages that encodes diphtheria toxin. DtxR, consists of two 25.3-kDa three-domain subunits and is a member of a family, of related repressor proteins in several Gram-positive bacterial species, some of which are important human pathogens. In this paper, we report on, the first high resolution crystal structures of apo-DtxR in two related, space groups. In addition, crystal structures of Zn-DtxR were determined, in the same two space groups. The resolutions of the structures range from, 2.2 to 2.4 A. The four refined models of the apo- and the holo-repressor, exhibit quite similar metal binding centers, which do, however, show, higher thermal motion in the apo-structures. All four structures reported, differ from each other in one important aspect. The N-terminal DNA-binding, domain and the last 20 residues of the dimerization domain of each subunit, move significantly with respect to the core of the DtxR dimer, which, consists of residues 74-120 from both subunits. These results provide the, first indication of a conformational change that may occur upon binding of, the holo-repressor to DNA.
About this Structure
1BI0 is a Single protein structure of sequence from Corynebacterium diphtheriae with ZN and SO4 as ligands. Full crystallographic information is available from OCA.
Reference
Motion of the DNA-binding domain with respect to the core of the diphtheria toxin repressor (DtxR) revealed in the crystal structures of apo- and holo-DtxR., Pohl E, Holmes RK, Hol WG, J Biol Chem. 1998 Aug 28;273(35):22420-7. PMID:9712865
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